1. Field of the Invention
This invention relates to a method of recording and reproducing a color video signal.
2. Description of the Prior Art
A method of recording a color video signal is disclosed in Japanese Patent Laid-Open Application No. 63-194494 wherein first and second color signals of a color video signal, which is composed of a brightness signal and such first and second color signals, are converted into a line sequential signal and then time base compressed, whereafter they are multiplexed with the brightness signal (into a horizontal blanking period of such brightness signal), and then the thus multiplexed signal (color line sequential TCI (time compressed integration) signal or color line sequential TDM (time division multiplexed) signal) is time base elongated to almost twice and then divided into signals of two channels, whereafter such signals of two channels for one field are recorded simultaneously onto two tracks by two (or three) scanning operations.
Such color line sequential TCI signal as described above is a high definition television signal wherein one frame includes a total of 1,125 scanning lines and effective lines of a first field range from the 40th to 557th lines while effective lines of a second field range from the 603rd to 1,120th lines. First and second time base compressed color signals to be multiplexed with a brightness signal Y are a wide band color signal Cw and a narrow band color signal Cn, respectively.
A video tape recorder records and reproduces such color line sequential TCI signal as mentioned above. Referring to FIGS. 8A to 8D, signals of two channels obtained by time base elongating and shuffling a color line sequential TCI signal for one frame are shown. Such signals are supplied by way of an emphasis circuit and an FM modulating circuit to an recorded by a rotary magnetic head apparatus.
Such rotary magnetic head apparatus includes four rotary magnetic heads mounted on a rotary drum of a tape guiding drum apparatus, and two sets of such rotary magnetic heads each including a pair of the rotary magnetic heads disposed adjacent each other are disposed in an angularly spaced relationship by an angle of 180 degrees from each other. The magnetic gaps of the adjacent rotary magnetic heads in each set have different azimuth angles from each other, and the azimuth angles of the magnetic gaps of the four rotary magnetic heads are set such that, when the four rotary magnetic heads rotate one full rotation, four inclined tracks may be formed at sucessively different recording azimuth angles on a magnetic tape.
Thus, when the four rotary magnetic heads rotate two full rotations, four sets of segment inclined tracks are formed simultaneously for each two tracks on a magnetic tape in accordance with recording signals 1 supplied to the four rotary magnetic heads. FIGS. 8A to 8D illustrate construction of such recording signals S1 (T1, T2), S2 (T3, T4) S3 (T5, T6) and S4 (T7, T8) for each 1/2 field. In FIGS. 8A to 8D, each numeral denotes a line number of a brightness signal Y (reference character Y is omitted) or a color signal Cw or Cn.
In this instance, the line signals for the brightness signal Y are distributed in the order of the recording signals T1, T2, T3, T4, T3, T4, T1, T2, T1, T2, T3, T4, T3, T4, T1, T2, . . . of the segment inclined tracks and in the order of the recording signals T5, T6, T5, T8, T7, T8, T5, T6, T5, T6, T7, T8, T7, T8, T5, T6, . . . Meanwhile, the color signals Cw and Cn are disposed alternately for each line for the recording signals T1 to T8 of the segment inclined tracks, and besides, colors signals of the first lines of the recording signals S1 to S4 of the segment inclined tracks in each pair are disposed alternately like Cw, Cn, Cw, Cn, . . .
When such recording signals as shown in FIGS. 8A to 8D are supplied to the rotary magnetic head apparatus described above and recorded onto a magnetic tape, such a recording pattern 1' as shown in FIG. 7 is formed on the magnetic tape. Referring to FIG. 7, reference characters Ach and Bch denote two segment inclined tracks onto which signals are recorded simultaneously; and each numeral denotes a line number of a brightness signal while line numbers for color signals Cw and Cn are omitted. It is to be noted that characters W and N in FIG. 7 correspond to Cw and Cn in FIGS. 8A to 8D, respectively. The recording signals T1, T3, T5 and T7 for a 1/2 field of the recording signals in FIGS. 8A to 8D are recorded on the sequential tracks Ach extending from the bottom to the top in FIG. 7 while the recording signals T2, T4, T6 and T8 are recorded on the sequential tracks Bch extending similarly from the bottom to the top. It is to be noted that the positions of the recording signals S1 to S4 of the segment inclined tracks in each pair on the magnetic tape are displaced sequentially by a distance corresponding to 0.5 H (H is a length on the magnetic tape corresponding to a horizontal period).
Such conventional color video signal recording method is advantageous in that joint portions when recording signals for one field are recorded onto a magnetic tape by two scanning operations can be hidden above and below a reproduction screen; that, is due to shuffling, even if one of recording signals of two channels recorded simultaneously with each other drops out, upon reproduction, due to clogging of a rotary magnetic head, a color picture image of an ordinary hue can be reproduced; that is, since a particular relationship is established between color signals of adjacent tracks, reduction of crosstalk can be achieved; and so forth.
Meanwhile, there is no trouble when color video signals recorded on a magnetic tape in accordance with such conventional color video signal recording method as described are reproduced by means of rotary magnetic heads while the magnetic tape is fed at a same speed as that upon recording. However, when the magnetic tape is reproduced while it is fed at a speed different from that upon recording, that is, in the case of different speed reproduction, there is the possibility that a color signal of a reproduction line signal of a line signal recorded at a starting end of each segment inclined track or of another reproduction line signal reproduced first after track jumping and another color signal of a different reproduction line signal immediately prior to such reproduction line signal may be reproduced in a wrong order, which will cause a displacement in hue of a reproduction color video signal.